Liquid crystal display devices are used in watches, calculators, various measuring instruments, automobile panels, word processors, electronic notepads, printers, computers, televisions, clocks, advertizing boards, and the like. Representative examples of liquid crystal display modes include a TN (twisted nematic) mode, an STN (super twisted nematic) mode, a vertical alignment mode that uses TFTs (thin film transistors), and an IPS (in-plane switching) mode. The liquid crystal compositions used in these liquid crystal display devices are required to be stable against outer factors such as moisture, air, heat, and light, have a liquid crystal phase in a temperature range as wide as possible about room temperature, have a low viscosity, and operate at a low drive voltage. A liquid crystal composition is constituted by several to several tens of compounds in order to optimize, for example, the dielectric anisotropy (Δ∈) and/or the refractive index anisotropy (Δn) for individual liquid crystal display devices.
In vertical alignment (VA) mode displays, a liquid crystal composition having negative Δ∈ is used. In horizontal alignment mode displays such as TN mode, STN mode, and IPS (in-plane switching) mode displays, a liquid crystal composition having positive Δ∈ is used. A drive system in which display is conducted by vertically aligning a liquid crystal composition having positive Δ∈ when no voltage is applied and by applying a transverse electric field has also been reported. This further increases the demand for liquid crystal compositions having positive Δ∈. In all drive systems, low-voltage driving, high-speed response, and a wide operating temperature range are required. That is, it is required that the absolute value of positive Δ∈ is high, the viscosity (η) is low, and the nematic phase-isotropic liquid phase transition temperature (Tni) is high. Furthermore, to control Δn×d, which is a product of Δn and cell gap (d), to be a desired value, Δn of the liquid crystal composition needs to be adjusted in an appropriate range in accordance with the cell gap. In addition, since an importance is given to high-speed response when liquid crystal display devices are applied to televisions or the like, a liquid crystal composition having a low rotational viscosity (γ1) is demanded.
For example, a liquid crystal composition that contains a liquid crystal compound having positive Δ∈ and represented by formula (A-1) below or formula (A-2) below and a liquid crystal compound having neutral Δ∈ and represented by formula (B) below in a combined manner has been disclosed as a liquid crystal composition with the aim of achieving high-speed response. The features of such a liquid crystal composition are that the liquid crystal compound having positive Δ∈ has a —CF2O— structure and the liquid crystal compound having neutral Δ∈ has an alkenyl group. These features are well-known in the field of liquid crystal compositions (refer to PTLs 1 to 4).

With the increasing number of applications of liquid crystal display devices, methods of using the liquid crystal display devices and methods of producing the liquid crystal display devices have also been markedly changed. In order to catch up with these changes, it has been desired to optimize properties other than known basic physical properties. Specifically, regarding liquid crystal display devices that use a liquid crystal composition, VA mode liquid crystal display devices, IPS mode liquid crystal display devices, and the like have been widely used, and very large display devices having a 50-inch or larger display size have been practically used. Regarding a method for injecting a liquid crystal composition into a substrate, with the increase in the substrate size, a one-drop-fill (ODF) method has been mainly used instead of an existing vacuum injection method. However, it has been found that a drop mark formed when a liquid crystal composition is dropped onto a substrate results in a problem of a decrease in the display quality. Furthermore, in the production process of liquid crystal display devices by the ODF method, an optimum amount of liquid crystal needs to be dropped in accordance with the size of a liquid crystal display device. If the amount of liquid crystal dropped highly deviates from the optimum amount, the predesigned balance of the refractive index and driving electric field of the liquid crystal display device is lost, which causes display defects such as formation of spots and contrast defects. In particular, in small-size liquid crystal display devices heavily used for fashionable smart phones, the optimum amount of liquid crystal dropped is small and thus it is difficult to control the deviation from the optimum amount within a particular range. Therefore, to maintain a high production yield of the liquid crystal display device, for example, it is necessary that the liquid crystal composition is less affected by a sudden change in pressure in a dropping device and an impact that occur when liquid crystal is dropped and thus the liquid crystal composition can be continuously dropped in a stable manner for a long time.
As described above, liquid crystal compositions used for active-matrix driving liquid crystal display devices that are driven with a TFT device and the like need to be developed in consideration of a method for producing a liquid crystal display device in addition to properties such as high specific resistance, high voltage holding ratio, and stability against outer factors, e.g., light and heat, to which an importance has been conventionally given, while maintaining the properties and performance required for liquid crystal display devices, such as high-speed response.